Vending Machine External Heat Exchanger

ABSTRACT

A vending machine cooling system incorporating R290 or other flammable refrigerant where there is no risk of the flammable refrigerant leaking inside the vending machine and possibly being ignited, through use of an unjointed dual walled refrigerant transport structure within the evaporator assembly positioned within the interior of the vending machine.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains material which is subject to copyright or mask work protection. The copyright or mask work owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright or mask work rights whatsoever.

FIELD OF THE DISCLOSURE

This disclosure relates to the use of new refrigerants in vending machines.

Governments across the globe are limiting the refrigerants that are potentially harmful to the earth. As a result, companies are starting to use r290 (propane) as a refrigerant including vending machine manufacturers. However, a problem with r290 is that it's flammable.

INTRODUCTION

Vending machines offer unattended sales of commodities such as snacks, canned or bottled beverages, or any of a variety of other articles. Frequently, these vended articles need to be kept cold or refrigerated and internal coils with refrigerants have traditionally been used to accomplish that cooling.

In the global transition away from high-global warming potential (GWP) hydrofluorocarbon (HFC) refrigerants, R-290 (aka propane) has emerged as an increasingly viable alternative.

Offering excellent thermodynamic properties and a very low GWP (GWP=3), this natural hydrocarbon refrigerant has potentially widespread uses in commercial refrigeration. But with its classification as an A3 (flammable) refrigerant, R-290's inherent safety concerns have always been a barrier to wider adoption.

Originally introduced in the early 1900s, R-290 was a commonly used refrigerant until it was replaced by chlorofluorocarbons (CFCs) in the 1930s. Since the 2000s, global regulatory actions to phase down high-GWP HFCs have led to a resurgence in the use of R-290 in smaller, self-contained applications.

Because R-290 is more combustible than HFCs special use considerations for using it in refrigeration applications can include use of sealed, gas tight, or fire and explosion proof electrical components, spark free fan motors, and ventilation and leak sensors or detectors.

In addition, there are UL specifications for refrigerated vending machines which have been published under a designation UL-541. One part of what is defined as being a protected system under subsection SA2.6 of Supplement SA states that any part of the refrigeration system located inside a vender, and in which the refrigerant is contained, in an enclosure which itself is contained within a separate protective enclosure. If leakage from the containing enclosure occurs, the leaked refrigerant is contained within the separate protective enclosure and the vender will not function as in normal use. The protective enclosure contains no joints within the vender.

These regulations do not specify specifically what any protective enclosure should be, nor its design.

DESCRIPTION OF PRESENTLY PREFERRED EXAMPLES OF THE INVENTION Brief Description of Figures

The invention is better understood by reading the following detailed description with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a vending machine;

FIG. 2 is a left side view of a vender with portions cut away to show additional structures in more detail;

FIG. 3 shows a frontal view with portions cut away for clarity;

FIG. 4 shows a vender right side with portions cut away to show the air flow path within the vender;

FIG. 5 show a diagrammatic view of the double walled refrigeration tubing;

FIG. 6 is a perspective view of the assembled inner heat exchanger portion of the cooling system;

FIG. 6A is an end view of one of the inner heat exchanger's finned sections;

FIG. 6B is a side view of an interior side of the finned section of FIG. 6A;

FIG. 7 is a perspective view from the left side, with portions cut away, showing the assembled interior evaporator assembly and connections to the exterior portion of the vending machine's cooling system;

FIG. 8 shows a cut away view of the interior and exterior portions of the vender cooling system; and

FIG. 9 is a rear view of the exterior portion of the vender cooling system with portions cut away for clarity

DETAILED DESCRIPTION OF THE INVENTION A. Overview

To gain a better understanding of the invention, a preferred embodiment will now be described in detail. Frequent reference will be made to the drawings. Reference numerals or letters will be used throughout to indicate certain parts or locations in the drawings. The same reference numerals or letters will be used to indicate the same parts and locations throughout the drawings, unless otherwise indicated.

B. Environment

One preferred embodiment will now be described with respect to a vending machine refrigeration system. The scale of the embodiment, therefore, is to be understood with respect to this type of article and environment. It is to be understood as well, however, that the invention is applicable to other articles and its scale can vary accordingly.

C. Structure

Turning to FIG. 1 a vending machine 10 typically includes an outer case having a front door 12 that includes a glass window 13, a top 14, side panels 16 and 18, a rear wall 20, and a bottom 22 from which legs 24 can extend to the floor. The front door 12 typically includes a retrieval door 26 leading to a hopper 28 as shown in FIG. 2 . The front door 12 can include vending machine controls and payment devices 30, or these can be in a separate vertical stack adjacent the door 12. FIG. 2 shows the front glass window 13 and one of a plurality of product trays 32 that extend horizontally across the machine's interior and are spaced apart and stacked vertically as shown in FIG. 1 .

Since this particular vending machine is refrigerated, the outer walls are each insulated by sheets of insulation 40 as shown in FIGS. 2 and 4 , for example. FIG. 2 also shows the refrigeration system comprised of an interior portion 50 and an exterior portion 100.

FIGS. 2-4 also show an internal air circulation path that can, for example, include a plenum 34 positioned vertically from a point adjacent the bottom and extending upwardly along the inside of the right interior wall from the internal refrigeration system 50, to provide air flow across the top of the interior space with the air flow then moving down through and around the stacked product trays back to the refrigeration unit 50. This is shown by the arrows in FIG. 3 .

The internal portion 50 of the refrigeration system is comprised of an outer frame 52, shown in FIG. 3 , for example, that can be mounted to an inner surface of the rear wall 20, a cover 54 shown in FIG. 2 , an evaporator coil assembly 56, and a circulation fan 58 mounted on the left side of the evaporation coil assembly 56, as shown in FIG. 4 .

Additional structural details of the internal evaporator assembly a simplified version of the approach is show in in FIG. 5 showing a portion of the rear wall 20 through which a double walled tubular structure 60 extends. The double walled tubular structure 60 is comprised of an outer tube 62 and an inner tube 64. The outer tube 62, for example, can have a wall thickness ranging from 0.01 inch to 0.040 inch, and a diameter of 1.5 inches, but could range in diameter from ⅜ inch to about 2 inches. The inner tube 64, for example, can have a wall thickness ranging from 0.015 inches to 0.040 inches, and a diameter of, for example, about ⅜ inch but could range from 3/16 inch to ½ inch. These differing diameters provide an internal space 66 between the two tubes 62 and 64. The double walled tubing 60 extends outwardly beyond the exterior of rear wall 20 where brazed, soldered, or welded joints at fittings 68 and 70 between the two tubes are provided. The inner tube 64 will be the tube through which the R290 refrigerant is being transported.

Also shown in FIG. 5 is a fill hole channel 72, that could, for example, be provided in the fitting 68 connecting the outer tube 62 to the inner tube 64. This fill hole channel 72 permits addition of a heat exchange medium into space 66 between tubes 62 and 64. That fill hole channel 72 is closed by a removable cap 74 that can be screwed, brazed, glued or otherwise removably fixed over the fill hole channel 72.

FIG. 5 also shows an expansion valve assembly 76 that changes a high-pressure liquid into a low-pressure liquid/vapor that will flow through inner tube 64 and through the evaporator coil assembly 56 where the low-pressure liquid/vapor will absorb heat from within the vending machines interior.

The space 66 between tubes 62 and 64 can be left open to provide a fail-safe way to capture therein any leaks of the R290 refrigerant from the inner tube 64 to prevent any leaking of the flammable R290 refrigerant into the vending machine and from potentially resulting in a fire within the vending machine. However, as suggested above, it is preferred to provide a good conductor material within that space 66, or some other heat exchange media within the space 66 which can be, for example, a solid, liquid or a gas. Ideally, a great media material would be one that could be installed as a liquid through fill hole 72 and then become more solid after the inner space 66 is filled so there would not be any leakage. Among the preferred media material is ethylene glycol, propylene, or silicone. To achieve the desired level of cooling within the interior of the vending machine the inner tube 64 should have an inner volume of about 24 cubic inches and the outer tube 62 should have a surface area of about 1900 square inches. The surface area of the outer tube 62 can be greatly reduced if fins are added such as those shown in FIG. 6A at 88. The outer tube 62 itself can have a surface area of, for example, over 500 square inches.

The interior portion of the heat exchanger includes the evaporator coil assembly 56 as shown in more detail in FIG. 6 . The double walled tubular structure 60 can be seen winding through an assembled evaporator assembly 80 that is comprised of a plurality of half sections 82 each of which is included as a pair of mating halves secured together around the coiled tubing. One of the half sections 82 is shown in more detail in FIGS. 6A and 6B.

FIGS. 6A and 6B each show one of the half or mating evaporator sections 82 of an evaporator assembly 80 as including a mating or flat inner wall 84 and a plurality of spaced apart, half round grooves 86 each of which extends along the full length of each of the half or mating sections 82. The exterior of each half or mating section 82 is provided with a plurality of outwardly extending fins 88 that also extend the full length of the half or mating section 82. The inner mating wall 84 is also provided with a series of through holes 90 so that bolts or a suitable connector can be used to hold two halves together tightly to and around tube 60 as shown in FIG. 6 .

The half section 82 are preferably made from aluminum, but other materials could also be used such as steel, copper, or other desired material.

Referring again to FIG. 6 , it can be seen that the double walled tube 60 has been shaped to form a coiled structure with curved ends and straight sections joining the curves that collectively forming a stack of spaced apart coils that wind around with one section on top of another forming a stack. While the size of the evaporator assembly 80 can vary depending upon the size of the vending machine and the internal area to be cooled, in one exemplary assembly the total length of tubing 60 could be about 271 inches. Then, pairs of the half sections 82 of the evaporation block are fitted onto the straight sections of tubing 60 and the adjacent pairs are then fixed together using bolts until all the straight sections are encased forming an assembled evaporator 80.

It should be understood that the plurality of half or mating blocks 82 could be formed as multiple pairs, as shown, or from two appropriately sized opposing units, to accommodate the desired number of coils in the tubing so that in either case opposing structures would encase a set of coils from opposing sides of the coiled tubing. Alternatively, material encasing each of the separate opposing sides of the dual walled tubing could be provided in the form of a heat removing structure otherwise formed there around, or the whole of the coiled double walled tubing could be encased within a molded structure formed with suitable evaporative heat removing surfaces.

FIGS. 2, 7, 8 and 9 show the exterior portion 100 of the refrigeration system that is mounted to the rear wall 20 and as FIG. 7 shows the assembled evaporator assembly 80 is mounted by a frame 52 adjacent the bottom of the vending machine, and the double walled tube 62 enters and exits through rear wall 20 to the exterior portion of the cooling system 100.

This exterior section 100 includes an outer cover 102 that has a bottom structure including air inlet perforations 104, and similarly perforated areas 106 at the top of the outer cover 102. These perforated areas permit ambient air to flow in from the bottom and exit the top due to air flow induced by an air circulation condenser fan 110 that is preferably mounted to an angled plate 112 within the exterior portion 100.

As was shown in FIG. 5 , the double walled tube 60 passes thorough rear wall 20 after which fittings 68 and 70 reduce tube 60 to the single walled tube 64. That single walled tube 64, which will now be located on the exterior of the vending machine, will be connected to a condensing coil assembly 120 located adjacent the bottom of the exterior portion 100 as shown in FIG. 8 , for example by a frame 121. The condenser coil assembly 120 can also include a finned outer portion to better the effect of the flow of ambient air flowing there over.

In operation, the refrigerant, as a low-pressure gas, passes through a compressor 122, mounted on a shelf 124 that is itself secured within the exterior portion 100 or directly to rear wall 20. The refrigerant flows from compressor 122 as a hot, high-pressure gas that is routed to and through the condenser coil assembly 120 which cools the high-pressure gas by which it becomes a high-pressure liquid. That high-pressure liquid is routed through a metering device, for example an expansion valve 76, causing a downstream pressure drop transforming the high-pressure liquid into a low pressure gas. The low-pressure gas then flows through the evaporator apparatus 80 within the vending machine 10 during which the refrigerant absorbs heat from within the vending machines interior. The refrigerant then flows as warmer, low-pressure gas passes back to compressor 122 for a continuation of the cycle.

D. Options and Alternatives

When introducing elements of various aspects of the present invention or embodiments thereof, the articles “a,” “an,” “the” and “said” are intended to mean that there are one or more of the elements, unless stated otherwise. The terms “comprising,” “including” and “having,” and their derivatives, are intended to be open-ended terms that specify the presence of the stated features, elements, components, groups, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, and/or steps and mean that there may be additional features, elements, components, groups, and/or steps other than those listed. Moreover, the use of “top” and “bottom,” “front” and “rear,” “above,” and “below” and variations thereof and other terms of orientation are made for convenience, but does not require any particular orientation of the components. The terms of degree such as “substantially,” “about” and “approximate,” and any derivatives, as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. For example, these terms can be construed as including a deviation of at least +/−5% of the modified term if this deviation would not negate the meaning of the word it modifies.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

What is claimed is:
 1. A cooling system for vending machines comprising: an outer casing having insulated top, bottom, front, rear and side walls collectively defining an interior vending space containing a plurality of product holding structures; an evaporator heat exchange system having a first interiorly mounted portion including a dual walled refrigerant transport tube positioned within the interior vending space, and a second exteriorly mounted portion employing single walled tubing operatively connected to the dual walled refrigerant transport tube so that refrigerant is cycled from the second exteriorly mounted portion to and through the dual walled refrigerant transport tube thereby providing a heat exchange mechanism in the vending space.
 2. The cooling system as in claim 1 wherein the dual walled refrigerant transport tube positioned within the interior vending space is a jointless structure.
 3. The cooling system as in claim 1 wherein the dual walled refrigerant transport tube comprises a smaller inner tube and a larger diameter outer tube positioned thereover.
 4. The cooling system as in claim 3 wherein the space between the inner and outer tubes is filled with a heat exchange medium.
 5. The cooling system as in claim 4 wherein the heat exchange medium comprises ethylene glycol.
 6. The cooling system as in claim 3 further including sealing fittings between the inner tube and the outer tube located exteriorly of the vending machine outer casing.
 7. The cooling system as in claim 6 further including a closable opening for inserting said heat exchange medium into the space within the dual walled refrigerant transport tube.
 8. The cooling system as in claim 3 wherein the inner tube has a volume of about 24 cubic inches and the outer tube has a surface area of about 1900 square inches.
 9. The cooling system as in claim 2 further including a finned structure positioned to overlie the dual walled refrigerant transport tube.
 10. The cooling system as in claim 9 wherein the finned structure is comprised of two finned structures each being spaced apart and each being formed from a plurality of segmented portions secured about a coiled section of the dual walled refrigerant transport tube.
 11. The cooling system as in claim 10 wherein each finned structure includes said plurality of segmented portions comprises a pair of connected portions.
 12. A cooling system for vending machines comprising: an outer casing having insulated top, bottom, front, rear and side walls collectively defining an interior vending space containing a plurality of product holding structures; an evaporator heat exchange system having a first interiorly mounted portion including a pair of opposing first and second segmented housings each comprised of a complementary shaped inner area shaped to receive tubing there within, the opposing first and second segmented housings being structurally interconnected and collectively supporting a dual walled refrigerant transport tube that is arranged to enter and extend through one shaped area in the first opposing segmented housing and to then exit from an opposite side of that first opposing segmented housing and to then curve and enter an inner area of the second of the opposing segmented housing and to then exit an opposite side of that second opposing segmented housing and then to curve back toward the first opposing segmented housing and into an adjacent shaped inner area with that winding of the dual walled refrigerant tube so as to form a continuous coil thereof along the length of the first interiorly mounted portion by passing back and forth between the inner shaped areas within the opposing segmented housings, the opposing segmented housings each having a heat exchange enhancing exterior; the dual walled refrigerant transport tube having an inlet end and an outlet end each extending beyond the first interiorly mounted portion and through the rear wall, and having fittings terminating the outer tube of the dual walled refrigerant transport tube exteriorly of the rear wall beyond which a single walled refrigerant tube extends; and a second exteriorly mounted portion including said fittings at the exterior inlet and outlet ends of the dual walled transport tube reforming the dual walled transport tube into said single walled refrigerant tube, a compressor for circulating refrigerant, a condenser coil connected to the single walled refrigerant by which heat is removed from the refrigerant as refrigerant is cycled there through, and an air circulator thereby collectively providing a heat exchange mechanism to cool the vending space.
 13. The cooling system as in claim 12 wherein the heat exchange enhancing exterior comprises a finned structure.
 14. The cooling system as in claim 12 wherein the dual walled refrigerant transport tube comprises an inner tube surrounded by a larger tube defining a space there between.
 15. The cooling system as in claim 12 further including a plurality of pairs of the opposing first and second segmented housings.
 16. The cooling system as in claim 12 wherein the dual walled refrigerant transport tube comprises an inner tube surrounded by a larger tube defining a space there between, and further including a closeable inlet into said space located exteriorly of the vending machine rear wall.
 17. A cooling system for vending machines comprising: an outer casing having insulated top, bottom, front, rear and side walls collectively defining an interior vending space containing a plurality of product holding structures; an internal portion comprising an evaporator heat exchanger consisting of first and second blocks each formed from opposing segments, the opposing segments each having an inner portion formed with a plurality of adjacent channels and an exterior portion including fins, the first and second blocks being interconnected and spaced apart, a jointless dual walled refrigerant transport tube arranged to interfit within the plurality of adjacent channels so as to form a continuous coil there within, the dual walled transport tube having an inlet end and an outlet end each extending outwardly beyond an exterior portion of the evaporative heat exchanger and each extending outwardly beyond an exterior portion of the outer casing; an external portion located outside of the vending machine including fittings at exterior ends of the dual walled transport tube reforming the dual walled transport tube into a single walled refrigerant transporting tube, a compressor for circulating refrigerant, a condenser coil connected to the single walled refrigerant transporting tube by which heat is removed from the refrigerant as refrigerant is cycled there through, and an air circulator thereby collectively providing a heat exchange mechanism to remove heat from and thereby cool the interior vending space.
 18. The cooling system as in claim 17 wherein the dual walled transport tube is comprised of a plurality of coils and said opposing segments comprise as plurality of segmented finned portions.
 19. The cooling system as in claim 17 wherein the opposing segments are molded in place about a plurality of coiled portions of the dual walled transport tube. 